1. Field of the Invention
The present invention relates to a coating structure, and particularly relates to a coating structure with an anti-reflection function and an anti-electromagnetic wave function.
2. Description of the Related Art
In the raw photo material production industry, an anti-reflection layer panel is the most important raw material. The importance of the raw optical-electrical material production industry is increasing while simultaneously there are growing requests for an improved yield, greater control of the process, reducing costs, and mass-producing for the optical-electrical product. The importance of the raw optical-electrical material production industry is almost the same as the semiconductor industry. The technology for producing anti-reflection layer panels is related to a variety of optical-electrical industries, such as LCD, OLED, FED, photo lens, etc. The specifications for an anti-reflection layer panel depend on the requirements of each industry. However, when a large dimension panel is produced, it needs to be composed of better raw material because for large dimension panels of the conventional art a nebulizing technique is used to create the surface structure.
The anti-reflection layer panel is a basic raw material for the optical-electrical industry. Almost all high-class panels use an anti-reflection layer panel. The anti-reflection layer panel and other electronic elements are assembled into an optical-electrical structure as an optical-electrical product to provide a specified function. For the anti-reflection layer panel, the desired characteristics are being light pervious and anti-reflection.
It is well known that the conventional layer structure for an anti-reflection optical coating has a general principle. This general principle is that the surface layer of the optical coating should be a material that has a low refractive index such as SiO2, with a refractive index of 1.46, or MgF2, with a refractive index of 1.38. However, when we apply the metal base anti-reflection coating on a display screen to create a high EMI shielding effect for a computer monitor, or low reflection glass for an LCD or a PDP, there are some bottlenecks in the process for high volume mass production. The basic reason for this is that the protective layer for example SiO2 or MgF2 of the optical layer structure is naturally porous and allows the H2O vapor to diffuse into the inside low resistivity metal thin layer to change the electric and optical characteristic of the layer system.
On the other hand, in the general design rule for an anti-reflection coating, the first layer deposited on the substrate surface is a material with a high refractive index (hereafter referred to as H), which is then followed by a second layer that is a material with a low refractive index (hereafter referred to as L). The basic design rule for the conventional anti-reflection coating is that there is a layer structure such as HLHL or HLHLHL. In a simple case, if the materials of H are ITO and the materials of L are SiO2, the 4-layered structure is glass/ITO/SiO2/ITO/SiO2. Because ITO is a transparent conductive material, the multi-layer coating of this layer structure has electrical conductivity of less than 100 Ω/square, and can be used as an EMI shielding and/or electric static discharge when the conductive coating layer is bonded to the ground. However, electronic circuits have moved to faster speed and more powerful functions, and extreme low resistivity, namely ≦0.6 Ω/square, is required to provide better EMI (Electronic magnetic Interference) shielding. Conventional multi-layer ITO coatings have good performance in the resistivity range of several Ω/square. However, resistivities below 1.0 Ω/square much increase the difficulty of mass production and result in very high cost of the final product.
On the other hand, although a thin metal layer has good electrical conductivity, metal also has many limitations for forming a multi optical layer system.
A well know phenomenon of thin film metal layers is their limited durability. Once water vapor diffuses into the surface and contacts the thin metal layer, an oxidation process will occur spontaneously and finally change the chemical property of thin metal layer and significantly change the electrical and optical characteristic of the optical layer system. A design of special compound layer was used as a surface protect layer for this invention. This surface protective layer is composed of Titanium oxide, Silicon dioxide and Aluminum oxide. The protective layer is an effective diffusion barrier to prevent the water vapor diffuse from the surface into inner metal layer.